The relative usefulness of automated apolipoprotein A-I and high-density lipoprotein cholesterol assays as markers for coronary artery disease

Research studies have shown that apolipoprotein A-I (apo A-I) is a better marker for coronary artery disease (CAD) than high-density lipoprotein cholesterol (HDLC). Yet, it is unclear whether assays for apolipoprotein A-I, which is part of macromolecular lipoprotein complex, can perform as well when measured by routine automated clinical laboratory techniques. The purpose of this study was to compare automated apolipoprotein A-I assays with HDLC as a marker for CAD. The authors studied two groups of angiographically documented men, aged 44-70 years, 42 with CAD and 123 without CAD in an unmatched, controlled study. Standard clinical laboratory techniques for assaying HDLC, and automated kit rate immunonephelometric, end point immunonephelometric, and immunoturbidimetric assays for apolipoprotein A-I were used. High-density lipoprotein cholesterol was a better marker than apolipoprotein A-I, according to the Mann Whitney test; HDLC also showed better diagnostic sensitivity, specificity, and predictive value. Using a precipitation method, HDL3 was a better marker than HDL2, but not as good as total HDLC. The authors concluded that HDLC remains the best routine single CAD marker commonly available for evaluation of HDL status in a high-risk population.